Method for ECG lead placement changes to be accurately accounted for

ABSTRACT

A method and system for electrocardiographic monitoring includes receiving cardiac signals recorded from electrodes attached to a patient according to a known electrode configuration and determining the known electrode configuration. The cardiac signal is then automatically analyzed based on the alternative electrode configuration. In one embodiment, the method includes acquiring a cardiac signal through electrodes connected to the patient according to a known electrode configuration and analyzing the cardiac signal to detect whether the known electrode configuration deviates from a standard 12 lead ECG configuration. If a deviation is detected, then an estimated electrode configuration is determined for the electrodes connected to the patient and the estimated electrode configuration is presented to a user. Confirmation information is received from the user regarding whether the estimated electrode configuration is the known electrode configuration, and the physiological data is automatically analyzed based on the confirmation information.

BACKGROUND

In cardiac monitoring clinicians often need to vary electrode placement in order to meet specialized physiologic and for monitoring needs of a patient. In electrocardiography (ECG), for instance, clinicians often utilize electrode configurations other than the standard 12 lead ECG. For example, some clinical guidelines suggest the use of right-sided chest (precordial) leads for pediatric and neonatal applications. Schwartz. P. J., et al. “Guidelines for the Interpretation of the Neonatal Electrocardiogram: A Task Force of the European Society of Cardiology.” European Heart Journal 23 (2002): 1329-1344. Likewise, right-sided chest (precordial) leads may be used in clinical applications relating to detection and treatment of certain myocardial infarctions (heart attacks). Antman, Elliott M., et al. “ACC/AHA Guidelines for the Management of Patients with ST-Elevation Myocardial Infarction.” ACC/AHA Practice Guidelines (2004): Kligfield, Paul, et al. “Recommendations for the Standardization and Interpretation of the Electrocardiogram: Part I. The Electrocardiogram and Its technology: A Scientific Statement From the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society Endorsed by the International Society for Computerized Electrocardiology.” Circulation, Journal of the American Heart Association 115 (2007): 1306-1324. Additionally, some clinical guidelines suggest the use of posterior leads for posterior myocardial infarctions. Id. Moreover, clinicians may use an alternative lead placement for a host of other reasons, including patient injury, such as a lesion at the site of standard electrode placement, and dextrocardia.

Current cardiac monitoring systems, including ECG systems, do not account for such alternative electrode placements that differ from a standard placement, and the systems do not automatically adjust their processing of the cardiac signal to correspond with the alternative electrode placement. Thus, current systems often misanalyze cardiac signals recorded from electrodes in alternative configurations because they analyze the signal as if it were recorded using a default, or standard, configuration, which results in the system providing inaccurate interpretations of the cardiac signal and incorrect suggestions for diagnoses.

SUMMARY

The present inventors recognize that the current systems and methods of electrocardiographic (ECG) monitoring, as well as other monitoring and diagnostic systems and methods, do not detect changes in electrode placement from standard configurations to other known configurations that are clinically useful or non-standard electrode placement that is medically necessary for patient care. Likewise, current systems and methods do not allow a user to input such intentional changes to electrode placement into the system in real-time so that the monitoring system can adjust its processing and analysis algorithms. Accordingly, the inventors devised the system and method disclosed herein, which detects changes from the expected lead placement and/or allows a user to input lead placement changes so that the correct algorithm is used to analyze spatial characteristics of cardiac signals, such as ECG signals.

In one embodiment, a method of monitoring a cardiac signal of a patient gathered through at least three electrodes connected to the patient according to an alternative electrode configuration is disclosed, wherein the alternative electrode configuration is a known electrode configuration that differs from a standard 12 lead ECG electrode configuration. The method comprises determining an alternative electrode configuration and automatically analyzing a cardiac signal based on the alternative electrode configuration.

In another embodiment an electrocardiograph system comprises a monitoring device capable of receiving cardiac signals from electrodes attached to a patient according to a known electrode configuration. The system further includes an analysis module configured to request information from the user identifying the known electrode configuration and automatically analyze the cardiac signals based on the known electrode configuration.

In yet another embodiment, a method of conducting ECG monitoring of the patient comprises acquiring a cardiac signal through electrodes connected to the patient according to a known electrode configuration and analyzing the cardiac signal to detect whether the known electrode configuration deviates from a standard 12 lead ECG configuration. If a deviation is detected, then an estimated electrode configuration for the electrodes connected to the patient is determined, and the estimated electrode configuration is presented to the user. Confirmation information is then requested from the user regarding whether the estimated electrode configuration is the known electrode configuration. The physiological data is then automatically analyzed based on the confirmation information.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carrying out the disclosure. In the drawings:

FIG. 1 provides the exemplary embodiment of a system for monitoring a patient's cardiac signal.

FIG. 2 provides an exemplary embodiment of a method for monitoring a patient's cardiac signal.

FIG. 3 provides another exemplary embodiment of a method for monitoring a patient's cardiac signal.

FIGS. 4a-4c provide illustrations of exemplary alternative electrode configurations for electrocardiography.

FIG. 5 depicts one embodiment of a system for executing a method for monitoring a patient's cardiac signal.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary system 40 for monitoring a patient's cardiac signal. Monitoring system 40 comprises a cardiac monitor 8, such as an ECG monitor, an analysis module 10, a display 12, and an input device 16 through which a user 13, such as a clinician, interacts with analysis module 10. More specifically, in the embodiment of FIG. 1, monitoring system 40 monitors patient cardiac signals employing an ECG monitor 8 receiving signal data from electrodes connected to patient 14. In the exemplary illustration of FIG. 1, ten electrodes are connected to patient 14 according to a standard 12 lead ECG configuration 20. The standard 12 lead EGG configuration 20 is one possible known electrode configuration out of many known electrode configurations. As described herein, there are numerous clinical reasons for which an alternative electrode configuration 23 (exemplified in FIGS. 4a-4c ), which is a known electrode configuration other than a standard 12 lead ECG electrode configuration, may be used. In the standard 12 lead configuration 20, electrodes V1-V6, as well as the right arm electrode RA, left arm electrode LA, right leg electrode RL and left leg electrode LL are attached to the patient according to the standard 12 lead ECG configuration 20. The electrodes V1-V6, RA, LA, RL, and LL, record cardiac electrical signals from patient 14 and transmit those signals to ECG monitor 8. In the embodiment of FIG. 1, ECG monitor 8 then transmits the signals to analysis module 10.

One purpose of analysis module 10 is to analyze a cardiac signal, such as an ECG signal, and to detect whether a known electrode configuration of the electrodes on patient 14 differs from a default configuration of analysis module 10. The analysis module 10 may be configured to detect any known electrode configuration recognized in the art, or any subset thereof. Known electrode configurations include all standard, alternative, and otherwise recognized electrode configurations that are known in the art of cardiac monitoring, including nonstandard electrode configurations that are medically necessary given certain diagnoses or conditions of a patient. Known electrode configurations may include configurations having any number of electrodes or leads, including, without limitation, configurations having 8, 10, 12, or 14 electrodes. As described above, there are several reasons why a user 13 might use an alternative electrode configuration 23 when collecting cardiac data. For example, a user 13 may utilize a right chest electrode placement in which electrodes are placed on the right side of the chest. The right chest electrodes may be in placed on the patient in addition to the standard V2-V6 electrode placement, or the right chest electrode placement may involve moving some or all of the V2-V6 leads to the right side of the patient's 14 chest rather than the left side as in the standard 12 lead ECG electrode configuration (see FIGS. 4b-4c for illustrations of right chest electrode placement). In other embodiments the known electrode configuration may be a posterior electrode placement, or may include limb lead changes, such as a Mason-Likar (see FIG. 4a ) arrangement, placing one or more of the limb electrodes RA, LA, RL, or LL onto the patient's torso instead of on the patient's limb(s). Analysis module 10 may further analyze and interpret the cardiac signal, for example to detect certain known diseases and/or conditions. Analysis module 10 may then output an interpretive statement of the cardiac signal listing any determinations made at the analysis stage.

In still other embodiments alternative electrode placement 23 may include nonstandard placements that are medically necessary or required, such as adjustment of one or more electrodes to accommodate a patient's 14 condition or injury. To provide one specific example, a user 13 administering an ECG to a patient with a left-side injury to their 6^(th) rib may not be able to utilize a standard 12 lead ECG electrode configuration and may need to use an alternative configuration wherein the V4 and V5 lead are moved. The analysis module 10 may detect such a change from the standard 12 lead ECG electrode configuration and may automatically analyze the cardiac signal based on the alternative electrode placement 23. For example, the analysis module 10 may use a different set of criteria for assessing the cardiac signals recorded from the alternative electrode placement 23. If appropriate, the analysis module 10 may perform a reduced analysis and produce a reduced set of interpretations that discounts or mores data, or a subset thereof, from certain electrodes.

In one exemplary embodiment pertaining to ECG, the default configuration is a standard 12 lead ECG configuration 20, and thus the analysis module determines whether the known electrode configuration is an alternative electrode configuration 23—i.e., a configuration that is different from the standard 12 lead ECG configuration 20. For example, the known electrode configuration depicted in FIG. 1 is standard 12 lead ECG configuration 20. If the default configuration for analysis module 10 is also standard 12 lead ECG configuration 20, then analysis module 10 would analyze the cardiac signal to determine that the known electrode configuration is equal to the default configuration. Analysis module 10 may then output an interpretive statement interpreting the cardiac signal accordingly. In other embodiments, the known electrode configuration is an alternative electrode configuration 23 that differs from the default configuration and analysis module 10 must determine the known electrode configuration, either by prompting the user for identification of the blown electrode configuration or by estimating it based on analysis of the cardiac signal.

FIG. 2 depicts one exemplary embodiment of a method of monitoring a patient, which is one exemplary embodiment of a method that may be executed by analysis module 10. A cardiac signal is received at step 41. The cardiac signal may be, for example, a cardiac signal recorded by ECG electrodes. Then, at step 43, analysis module 10 determines whether the cardiac signal differs from a model signal associated with a default configuration. For example, the default configuration could be standard 12 lead ECG electrode configuration 20. In an alternative embodiment, the model signal may be a previous recording from patient 14 taken at an earlier time using a previous electrode configuration, and the analysis module 10 may set the default configuration as the previous configuration. In such an embodiment, the model signal would be a recording from patient 14 using an electrode configuration that is identifiable by the system. In an exemplary instance, the model signal may be a previous ECG recording taken from the patient using a standard 12 lead ECG electrode configuration 20 and, accordingly, the default configuration may be set as standard 12 lead ECG electrode configuration 20. In an alternative embodiment, the previous ECG recording may be taken from the patient using any known electrode configuration and the default configuration may be set to correspond to that particular known electrode configuration. In still other embodiments, the model signal may be an exemplary reference signal identifying common features present in a typical signal taken according to a default configuration. In such an embodiment, the model signal may present a range of acceptability for determining that the known electrode configuration 20 connected to the patient 14 matches the default configuration used by the analysis module 10.

In one exemplary embodiment, the analysis module 10 may employ matrix mathematics at step 43 to analyze each of the cardiac signal and the model signal, and thereby to determine whether they differ from one another in any significant way. More specifically, the analysis module 10 may employ the Karhunen-Loeve transform (KLT), singular value decomposition, principal components analysis, or principal forces analysis, to discover a set of basis vectors or eigenvectors that organize the variability of data in a multi-dimensional space along new directions, orthogonal to each other and ranked in order of significance. For each eigenvector, a corresponding eigenvalue is calculated. In addition, eigenvalue coefficients are calculated which correspond to the portion of each eigenvector that is necessary to reconstruct each original lead vector recorded between two electrodes. From the eigenvector solution of the covariance matrix, the angles between the eigenvectors and the original vectors are determined. The eigenvalue coefficients and the angles between the eigenvectors and the original vectors are related by a cosine relationship. The angles calculated for each of the cardiac signal and the model signal can be compared to determine whether the electrodes are placed in the default ECG electrode configuration or a different known electrode configuration. In one alternative embodiment, the model signal may be a reference set of angles to which the angles calculated for the cardiac signal can be compared.

If the cardiac signal does not differ from the model signal at step 43 then analysis module 10 sets the known configuration as the default configuration. For example, in the embodiment depicted in FIG. 1 where the known configuration is a standard 12 lead ECG electrode configuration 20 and the default configuration is also the standard 12 lead ECG configuration 20, the known configuration is equal to the default configuration and thus would be correctly set at step 45. On the other hand, at step 43 if the cardiac signal differs from the model signal, then analysis module 10 proceeds to step 48 where it determines whether the difference between the cardiac signal and the model signal is consistent with one of a predefined set of differences. For instance, referring again to an ECG embodiment where the default configuration is the standard 12 lead ECG configuration 20, step 48 checks to see if the cardiac signal is different from the model signal in a way that is consistent with a known configuration. For example, if one or more of the signals associated with the leads is flipped up-side-down that may indicate that the known electrode configuration 20 of the electrodes attached to the patient 14 is a right chest electrode configuration wherein one or more of the V2-V6 electrodes is moved to the right side of the chest (such as shown in FIGS. 4b-4c ).

In one embodiment, the analysis module 10 has a predefined set of differences between the default configuration and a list of known electrode configurations 20. The predefined set of differences may be, for example, a database or list of possible differences between a model signal associated with a default configuration and each of a set of known signals associated with a set of known electrode configurations. If the difference between the model signal and the cardiac signal is consistent with one of the predefined differences in the set of predefined differences at step 48, then analysis module 10 progresses to step 50 where it determines the estimated electrode configuration. The estimated electrode configuration is determined as the configuration associated with the difference detected between the cardiac signal and the model signal. As mentioned above, this difference may be determined by comparing the difference between the cardiac signal and the model signal to a set of predefined differences, where each of the predefined set of differences is associated with a known electrode configuration. Thus, the estimated electrode configuration may be the known electrode configuration associated with the difference between the cardiac signal and the model signal.

At step 54 the estimated electrode configuration is then presented to the user for verification. The user verification may be conducted by any user interface means known in the art. In one embodiment, the estimated electrode configuration is presented to the user along with the option to confirm or reject the estimated electrode configuration as the known configuration of electrodes placed on the patient 14. If the user confirms that the estimated electrode configuration is equal to the known electrode configuration, then the analysis module 10 progresses to step 62 where it analyzes the cardiac signal based on the known electrode configuration. The analysis module 10 may be configured to automatically perform such analysis of the cardiac signal to account for the known electrode configuration, such as by automatically selecting and executing corresponding and appropriate analysis algorithms.

On the other hand, if the user rejects the estimated configuration, stating that the known configuration is not equal to the estimated configuration, the analysis module 10 proceeds to step 56 where it prompts the user to input the known electrode configuration. Likewise, if the difference between the cardiac signal and the model signal is not consistent with a predefined difference, then analysis module 10 may progress from step 48 to step 56 where it prompts a user 13 to input the known electrode configuration. For example, analysis module 10 may display a graphic demonstrating the default electrode configuration or the estimated electrode configuration on the display 12, wherein the placement of one or more of the electrodes represented on the graphic may be adjusted by the user 13. In such an embodiment the user 13 may be prompted to adjust the configuration on the display 12 to represent the known electrode configuration. In another embodiment the analysis module 10 may request that the user identify the known electrode configuration by name or otherwise describe the known electrode configuration. In still other embodiments the analysis module may provide a list of possible known electrode configurations, such as a drop-down list, and the user may select one configuration off of the list.

Once the user 13 enters information identifying the known electrode configuration and such information is received, analysis module 10 analyses the cardiac information based on the known electrode configuration at step 62. Lastly, at step 63 the analysis module 10 may output an interpretive statement. The interpretive statement may, for example, list any abnormalities or disease indicators detected in the cardiac signal by the analysis module 10. Alternatively or additionally, the interpretive statement may provide an estimated or predicted diagnosis. Additionally, the analysis module 10 may store on a storage medium the cardiac signal in association with the known electrode configuration and/or the interpretive statement.

Turning to FIG. 3, another embodiment of a method of monitoring the cardiac signal of a patient is demonstrated. At step 41, a cardiac signal is received, for example via at least three electrodes connected to the patient according to a known electrode configuration. The user is then prompted to input the known electrode configuration at step 56. As described above with respect to step 56, the user may be prompted to input the known electrode configuration by any means known in the art. Once the user inputs the known electrode configuration, analysis module 10 receives the known electrode configuration at step 58 and then analyzes the cardiac signal at step 62 based on that known electrode configuration. The analysis module 10 then outputs an interpretive statement 63.

In still other embodiments, a method of monitoring the cardiac signal of a patient may include receiving a cardiac signal recorded from a patient using a known electrode configuration and then comparing it to a model signal to determine whether the known electrode configuration differs from the default configuration (see steps 41 and 43 of FIG. 2). Then, if a difference is detected between the known configuration and the default configuration, the system may prompt the user to input the known electrode configuration (see step 56 of FIGS. 2-3). As described with respect to FIGS. 2 and 3 above, once the user inputs the known electrode configuration, the analysis module 10 receives the known electrode configuration (step 58), analyzes the cardiac signal (step 62) based on that known electrode configuration, and then outputs an interpretive statement (step 63).

FIGS. 4a, 4b, and 4c illustrate just a few of the possible alternative electrode configurations 23, which are known electrode configurations other than the standard 12 lead electrode configuration 20. FIG. 4a demonstrates a Mason-Likar configuration. In the Mason-Likar configuration, the limb electrodes, including the, right arm electrode RA, the left aim electrode LA, the right leg electrode RL and the left leg electrode LL, are moved into the torso of the patient 14. For maximal accuracy in analyzing the cardiac signal, the analysis module 10 preferably is able to detect the Mason-Likar configuration and to analyze the cardiac signal accordingly.

FIGS. 4b and 4c illustrate two possible embodiments of a right chest electrode placement. In a right chest electrode placement, one or more of the electrodes V2-V6 is moved to the right side of the chest. Such a configuration may be clinically called for when monitoring certain patients, such as pediatric patients, or patients with dextrocardia. In FIG. 4b , the right chest electrode placement includes right placement of all of the V2-V6 electrodes, which are labeled as V2 r, V3 r, V4 r. V5 r, and V6 r. Since the V2 electrode is moved to the right side, V2 r, the V1 electrode is moved to the left side, and is also labeled V1 r. FIG. 4c demonstrates a different right chest electrode placement wherein additional electrodes are placed on the right side of the chest in addition to the V1-V6 electrodes placed on the left side of the patients 14 chest. Thus, in the embodiment of FIG. 4c , twelve electrodes are used to monitor the patient instead of ten electrodes. Alternatively, the V3 and V4 electrodes could be moved to the right side to become the V3 r and V4 r electrodes, respectively. In such an embodiment, only ten electrodes would be used. In the embodiments depicted in 4 b and 4 c, the limb electrodes may be placed on the limbs as shown in FIG. 1, or on the torso as shown in FIG. 4a . Preferably, the analysis module 10 would accurately determine such placement of the limb electrodes.

FIG. 5 is a system diagram of an exemplary embodiment of a system 1200 for implementing an analysis module 10. The system 1200 is generally a computing system that includes a processing system 1206, storage system 1204, software 1202, communication interface 1208 that interfaces with exterior devices, such as the monitoring device that may provide the cardiac signal 67, and a user interface 1210. The processing system 1206 loads and executes software 1202 from the storage system 1204, including application module 1230. When executed by the computing system 1200, application module 1230 directs the processing system 1206 to operate as described in herein in further detail, including execution of the analysis module 10. The application module 1230 and/or the analysis module 10 may further instruct the system to store analysis data produced by the analysis module 10 in the storage system 1204. For example, the analysis module 10 may instruct storage of the cardiac signal along with the known electrode configuration and/or the interpretive statement in the storage system 1204.

Although the computing system 1200 as depicted in FIG. 7 includes one software module 1202 in the present example, it should be understood that one or more modules could cooperate to provide the same operation. Similarly, while description as provided herein refers to a computing system 1200 and a processing system 1206, it is to be recognized that implementations of such systems can be performed using one or more processors, which may be communicatively connected, and such implementations are considered to be within the scope of the description.

The processing system 1206 can comprise a microprocessor and other circuitry that retrieves and executes software 1202 from storage system 1204. Processing system 1206 can be implemented within a single processing device but can also be distributed across multiple processing devices or sub-systems that cooperate in existing program instructions. Examples of processing system 1206 include general propose central processing units, applications specific processors, and logic devices, as well as any other type of processing device, combinations of processing devices, or variations thereof.

The storage system 1204 can comprise any storage media readable by processing system 1206, and capable of storing software 1202 and other data. The storage system 1204 can include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modifies, or other data. Storage system 1204 can be implemented as a single storage device but may also be implemented across multiple storage devices or sub-systems. Storage system 1204 can further include additional elements, such a controller capable, of communicating with the processing system 1206.

Examples of storage media include random access memory, read only memory, magnetic discs, optical discs, flash memory, virtual memory, and non-virtual memory, magnetic sets, magnetic tape, magnetic disc storage or other magnetic storage devices, or any other medium which can be used to storage the desired information and that may be accessed by an instruction execution system, as well as any combination or variation thereof, or any other type of storage medium. In some implementations, the store media can be a non-transitory storage media. In some implementations, at least a portion of the storage media may be transitory. It should be understood that in no case is the storage media a propagated signal.

User interface 1210 can include a mouse, a keyboard, a voice input device, a touch input device for receiving a gesture from a user, a motion input device for detecting non-touch gestures and other motions by a user, and other comparable input devices and associated processing elements capable of receiving user input from a user. Output devices such as a video display or graphical display can display an interface further associated with embodiments of the system and method as disclosed herein. Speakers, printers, haptic devices and other types of output devices may also be included in the user interface 1210.

As described herein, the computing system 1200 receives cardiac signal 67 through the communication interface 1208. The cardiac signal 67 may be, for example, an ECG recording from three or more leads attached to the patient 14. In still further embodiments, the cardiac signal 67 may be streaming data received in real time or near-real time by the computing system 1200, or the cardiac signal 67 may be a previously recorded signal sent to the computing system 1200 for processing.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

We claim:
 1. A method of monitoring a cardiac signal of a patient gathered through at least three surface electrodes connected to the patient according to an alternative electrode configuration, wherein the alternative electrode configuration is one of a predetermined set of electrode configurations that differ from a standard 12 lead ECG electrode configuration, the method comprising: analyzing with a processor the cardiac signal to detect that the cardiac signal was recorded through an electrode configuration that differs from the standard 12 lead ECG electrode configuration, including detecting whether the cardiac signal differs from a model signal, wherein the model signal is associated with a default electrode configuration; determining with the processor the alternative electrode configuration from the predetermined set of electrode configurations; and automatically analyzing with the processor the cardiac signal based on the alternative electrode configuration.
 2. The method of claim 1 wherein the step of determining the alternative electrode configuration includes: requesting information from a user identifying the alternative electrode configuration.
 3. The method of claim 2 wherein the step of determining the alternative electrode configuration further includes: if a difference from the model signal is detected, determining an estimated electrode configuration based on the difference; and wherein the step of requesting information from the user identifying the alternative electrode configuration includes presenting the estimated electrode configuration to the user for verification.
 4. The method of claim 1 wherein the model signal is a previously recorded cardiac signal from the patient, wherein the previously recorded cardiac signal from the patient is associated with a previous electrode configuration; and wherein the default electrode configuration is the previous electrode configuration.
 5. The method of claim 3 wherein the step of requesting information from the user identifying the alternative electrode configuration further includes presenting the user with an option to deny the estimated electrode configuration and to manually enter the alternative electrode configuration.
 6. The method of claim 1 further comprising comparing the cardiac signal to the model signal to determine whether a difference between the cardiac signal and the model signal is consistent with any of a predefined set of differences, wherein each difference in the predefined set of differences corresponds with an estimated electrode configuration.
 7. The method of claim 6, wherein determining whether the difference between the cardiac signal and the model signal is consistent with any of a predefined set of differences includes determining whether the difference between the cardiac signal and the model signal is consistent with a right chest electrode placement.
 8. The method of claim 4 wherein, if the cardiac signal does not differ from the model signal, the estimated electrode configuration is determined to be the default electrode configuration.
 9. The method of claim 1 wherein the model signal is a template accounting for a range of expected values for the cardiac data based on the default electrode configuration.
 10. The method of claim 9 wherein default electrode configuration is the standard 12 lead ECG electrode configuration.
 11. A method of monitoring a cardiac signal of a patient gathered through at least three surface electrodes connected to the patient according to an alternative electrode configuration, wherein the alternative electrode configuration is one of a predetermined set of electrode configurations that differ from a standard 12 lead ECG electrode configuration, the method comprising: analyzing with a processor the cardiac signal to detect that the cardiac signal was recorded through an electrode configuration that differs from the standard 12 lead ECG electrode configuration, including: comparing the cardiac signal to a model signal associated with a default electrode configuration to determine whether a difference between the cardiac signal and the model signal is consistent with any of a predefined set of differences; wherein each difference in the predefined set of differences corresponds with an alternative electrode configuration in the predetermined set of electrode configurations; determining with the processor the alternative electrode configuration based on the difference between the cardiac signal and the model signal; and automatically analyzing with the processor the cardiac signal based on the alternative electrode configuration.
 12. The method of claim 11 wherein the model signal is a previously recorded cardiac signal from the patient, wherein the previously recorded cardiac signal from the patient is associated with a previous electrode configuration; and wherein the default electrode configuration is the previous electrode configuration.
 13. The method of claim 11 wherein the model signal is a template accounting for a range of expected values for the cardiac data based on the default electrode configuration.
 14. The method of claim 13 wherein default electrode configuration is the standard 12 lead ECG electrode configuration.
 15. The method of claim 11 further comprising: determining an estimated electrode configuration based on the difference between the cardiac signal and the model signal; and presenting the estimated electrode configuration to a user for verification.
 16. The method of claim 15 wherein the step of presenting the estimated electrode configuration to the user for verification includes presenting the user with an option to accept the estimated electrode configuration or an option to deny the estimated electrode configuration and to manually enter the alternative electrode configuration. 